Fluorite (calcium fluoride)
Color: Colorless, yellow, green, blue, pink, purple, red and orange.
Moh’s hardness: 4
Refractive index: 1.434
Critical angle: 44°
Specific gravity: 3.18
Cleavage: Perfect in 4 directions.
Fracture: Even to conchoidal, brittle.
Dispersion: Very low (.007)
Heat sensitivity: Low
Birefringence (double refraction): None
Crystal structure: Isometric
Treatments: May be irradiated.
Cutting: Orient the table about 10 degrees off the crystal face to reduce cleavage problems. Pre-polish with an extra fine lap.
Polishing: Tin/lead with alumina, chrome oxide Ultralap.